1. Field of Invention
This invention relates to an intercommunication unit and a system using such units, particularly to a visual intercommunication system utilizing portable terminal units having a display panel and a keyboard.
2. Description of Prior Art
In many offices and businesses there is a need for a compact, flexible communication system which allows personnel to intercommunicate in a simple, reliable, economical, and non-intrusive manner. Heretofore many types of intercommunication systems have been proposed, but each had significant drawbacks. Audio intercoms have been used, but these are intrusive, especially if the person called is engaged in another conversation, generally must be wired to be reliable, often have poor audio fidelity, and require the message receiver to reply immediately in order to inform the sender that the message has been heard. Video and hard copy intercommunications systems have been proposed, but these are large, expensive, require special wiring, and generally have other functions such as word processing, and therefore cannot be used for intercommunication while their other functions are in use. Hand-delivered slips of paper have also been used to communicate messages, but these obviously suffer from serious drawbacks in that they require the sender to walk into the receiver's office or area, which is difficult, awkward, and not feasible if a potential receiver is engaged in a private conference.
Another communication problem arises when a person leaves the office and wishes to leave an appropriate message, e.g., as to expected time of return, etc., with coworkers. Leaving a verbal message with a coworker or a note on the desk is fraught with obvious disadvantages of reliability.
Accordingly several objects of the present invention are to provide an intercommunication unit and system useable in offices and businesses, but which is compact, portable, inexpensive, requires no special wiring, can be used conveniently to generate, transmit, receive, store, and display messages, can be used while intended receivers of a message are engaged in a telephone conversation, or a private conference, without disturbing such intended receivers, can let a sender know that a message has been received without requiring action on the part of the receiver, and does not require the use of hand-carried slips. Further objects and advantages are to provide an intercommunication system which allows selective transmission from one station to any of a plurality of other stations, allows any station to transmit to any of a plurality of other stations and to determine which stations have received a message, allows any station to leave an automatic reply message when the user of such station will be away or preoccupied, requires no printers, hard-copy output devices, or other awkward means. Further advantages and objects of the invention will become apparent from a consideration of the ensuing description hereof.